1. Field of the Invention
The present invention relates to an imaging device, a focusing method for use with the imaging device, and a program.
2. Description of the Related Art
At present, digital cameras and film-based cameras are mostly equipped with autofocusing (AF) mechanisms. Among the autofocus systems built into these cameras are a phase difference detection system which brings the camera into focus by detecting a difference in incident light between different positions and a contrast detection system which achieves focus by detecting the lens position at which the contrast of an image captured on a CCD or the like becomes maximized. In either of the AF systems, poorly lit subjects often make it impossible to detect the correct lens in-focus position. For this reason, with such a shooting environment, an assist light beam is emitted to improve the subject environment.
Even in the case where a subject is irradiated with the assist light beam as described above, however, in some instances the decision of the correct lens in-focus position becomes impossible due to lack of the amount of light or an erroneous decision is made. In particular, irrespective of an out-of-focus condition, the user may be erroneously notified that the camera has been brought into focus. That is, the user may take a picture without knowing that focus is not achieved.
The incorporation of an assist light irradiation device or parts into cameras would increase the cost and impose restrictions on the camera size and design. Additionally, a person as a subject might be dazzled during autofocusing.